1. Field of the Invention
The present invention relates generally to rotatable electrical devices, such as switches, variable capacitors, and potentiometers, and, more particularly, but not by way of limitation, to a novel compact rotatable electrical device that reduces the volume occupied by conventional such devices in an electrical apparatus.
2. Background Art
Rotatable electrical devices are well known and include rotating switches, variable capacitors, potentiometers, and the like. In one application, such devices may be attached to an external surface of a radio. Typically, the device includes a stationary main control body disposed within the radio and connected to circuitry in the radio. Fixedly attached to and extending from the main control body is a hollow, externally threaded, cylindrical mounting bushing which extends through a hole defined in the external surface. A jamnut threaded on the mounting bushing is tightened against the outside of the external surface and secures the mounting bushing and main control body in place. Extending through the mounting bushing from the operative elements within the control body is a control shaft at the distal end of which external to the mounting surface is attached a knob.
A substantial disadvantage of the above conventional arrangement is that, with the requirement for some electrical apparatus, such as handheld radios, to become smaller and smaller, rotatable devices of the type noted above consume an increasingly greater percentage of the available volume within the apparatus.
A further disadvantage of the conventional construction of such devices is that the knobs thereof are frequently secured in place by means of set screws which can be loosened by vibration.
Another disadvantage of the conventional construction of such devices is that the hollow mounting bushing is a point of weakness and such bushings frequently break.
An additional disadvantage of the conventional construction of such devices is that the control shaft thereof is relatively long which presents a long lever arm and another point of weakness.
In some applications, protective ears have been provided on the mounting surface to protect the devices from breaking. These protective ears can consume valuable control panel space and hinder operation, in addition to representing additional manufacturing cost.
Yet another disadvantage of the conventional construction of such devices is that the jamnut is easily accessible from the outside surface of the panel and, thus, the apparatus is subject to tampering by removal of the jamnut.
Accordingly, it is a principal object of the present invention to provide a rotatable electrical device which is compact and occupies substantially less volume in an electrical apparatus than do conventional rotatable electrical devices.
It is further object of the invention to provide such a device that is strong.
It is an additional object of the invention to provide such a device that is easily and economically constructed.
It is another object of the invention to provide such a device that has a relatively short control shaft.
It is yet a further object of the invention to provide such a device that is relatively tamperproof.
Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures.